Various compounds have been disclosed for coloring hair. For example, U.S. Ser. No. 08/476,303 discloses several useful colorants. Example 13 describes the preparation of a polymer containing a difunctional blue anthraquinone colorant and Example 14 describes dispersing the blue polymer in hot water. It has been found that the dispersion of Example 14 is not stable and sludging results and the polymer is extremely difficult to disperse in contrast to the sulfo-polyesters prepared from the dyes of the present invention.
U.S. Pat. No. 4,999,418 discloses anthraquinone compounds having the formula AQNHCH.sub.2 C(R.sub.1)R.sub.2 CH.sub.2 X!.sub.n wherein AQ is the residue of a 9,10-anthraquinone radical; R.sub.1 and R.sub.2 are the same or different and are unsubstituted alkyl, cycloalkyl or aryl; X is a group reactive with at least one monomer from which polyester is prepared; n is 1 or 2. Column 2 (lines 35-38 ) provides the list of possible substituents on the anthraquinone ring. Included in this list of substituents is arylthio; however, diarylthio substituted anthraquinone compounds similar to those of the present invention are not disclosed. The compounds of Examples 61 and 86 contain only one arylthio group and the compound of Example 62 contains two methythio groups. Neither of these colorants has a desirable shade of blue and the colorant of Example 86 would be difficult to prepare on a commercial scale since in involves the use of the very volatile and odoriferous methylmercaptan.
U.S. Pat. No. 4,804,719 describes a variety of colorants which are useful for copolymerizing to prepare water-dissipatable polyester and polyester-amides containing a variety of copolymerized colorants. There is no disclosure of the anthraquinone compounds of the present invention, however.
U.S. Pat. No. 4,841,057 discloses 1,5-diamino-4,8-diarylthioanthraquinones. These colorants are not thermally stable when added to a polyester forming reaction and drastic color changes are observed in contrast to the colorants of this invention.